Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!RICEVM1.RICE.EDU!TROTH From: TROTH@RICEVM1.RICE.EDU (Rick Troth) Newsgroups: comp.lang.asm370 Subject: (none) Message-ID: <9001120113.AA16459@lilac.berkeley.edu> Date: 11 Jan 90 16:20:04 GMT References: Sender: daemon@ucbvax.BERKELEY.EDU Reply-To: IBM 370 Assembly Programming Discussion List Distribution: inet Organization: The Internet Lines: 43 >From the recent discussion on CTCA's, I have the impression that you >write a program that specifies the (virtual on CMS) addresses of the >coupled CTCA's as channel device addresses and then tramsmits data from >one to the other by means of an I/O program similar to one you would >write for a DASD (disk). Yes. Except that you would not have to do any SEEKs :-) > ... I thought that instructions like RDD (Read Direct) , >WRD (Write Direct) and SIGP (Signal Processor) would be used in a CTCA >program. No ... SIO (Start I/O), TIO (Test I/O), and cousins. READ/WRITE DIRECT use an 8-bit path, only ONE path at that, not 4096 or 8192 or 65536 possible addresses as with normal 370 I/O. You want to go the Start-I/O route, which means you'll need to learn to write "channel programs". But I think you'll find that channelized I/O is better in many respects. >I have a System/370 Reference Summary, Fourth Edition, November 1976. >Is it too out-of-date to be reliable? It IS out of date, but hang on to it! After version 4 of that reference, they removed mention of certain virtual control bits, which are only meaningful in a virtual control register of a virtual machine. The reference now deals only with real hardware, I believe. > I know that the CMS nucleus, whose >layout is described by the macro NUCON, occupies the low end of memory >in the virtual machine. Actually, CMS lives in hign memory, usually a DCSS (virtual ROM) beyond your machine's virtual RAM. > In that case, where are the Fixed Storage Locations, beginning >with IPL PSW, IPL CCW1, IPL CCW2 etc. ... Those are in the addresses listed in your reference. You can do a CP DISP vaddr to examine them, or a CP STORE vaddr value(s) to change them; be careful! REXX provides the STORAGE function. In ASSEMBLEr programs, you can refer to any virtual address you like. Rick Troth ------------- Rice ONCS VM Systems Support